Low frequency electromagnetic systems have a wide variety of applications, such as radio communication and navigation, as well as various medical, meteorological and military applications. In particular, low frequency systems are often used to communicate information to or from a system that is enclosed by a conducting material, for example, salt water, metal containers, buildings, soil, tissue, and so forth. A conductive material that intercepts the source will generate eddy currents that oppose the impinging field. Traditional radio frequency systems are generally not capable of supporting these types of applications since radio frequency (“RF”) signals (in the Mhz-GHz frequency range) cannot penetrate even a moderate thickness of a surrounding conductor. Accordingly, low frequency electromagnetic systems offer a way to penetrate these barriers for communication and localization in what would ordinarily be considered a denied environment.
Traditional RF signals are typically line-of-sight signals and require a satellite link for long range operation. However, satellites are not always reliable, especially in wartime situations where they may be jammed or otherwise unavailable. In comparison, operating in the medium frequency band (“MF”) (0.3 MHz-3.0 MHz), and below, enables propagation over long distances assisted by refraction from the Earth's ionosphere. This principle can leverage signals in the very-low frequency band (3.0 kHz-30.0 kHz) to enable worldwide communications.